1. Field of the Invention
The present invention broadly relates to an arm restraint system and, more particularly, is concerned with a simple, non-restrictive system designed to allow unimpeded arm and body movement during normal aircraft operation, as well as protection for an aircrewman from arm flail injuries during high speed emergency ejection from the aircraft.
2. Description of the Prior Art
Ejection of aircrewmen from aircraft traveling at velocities above 375 KEAS (knots estimated air speed) has resulted in a windblast injury rate in excess of ten percent. At 500 KEAS, the probability of injury is nearly fifty percent. The injuries that are experienced range from joint derangements and long bone fractures to catastrophic extension of the cervical spine. Even where crewmen survive such injuries, they often need to undergo long recovery periods, and in case where there is joint disruption or nerve involvement, return to flight status may not be possible.
Voluntary action of the crewman cannot be relied upon to maintain his body members in their optimum positions for ejection. Therefore, various positioning and restraining devices have been developed for forcing his body members into those positions and confining them therein. Several devices known heretofore for positioning a crewman's body members in predetermined positions in relation to an ejection seat utilize some sort of tension lines or the like which are rendered operative to effect such positioning by the motion of the ejection seat and seat occupant relative to the aircraft. In the actuation of these tension lines, the work required for moving the occupant's body members to their ejection positions is derived from the propulsion means that effects seat ejection.
U.S. Patents to Bohlin, No. 3,074,669; Stanley, No. 3,502,073; Miller et al, No. 3,957,231; and Yamada, No. 4,179,086; and British Specification No. 1,456,007 to Martin all disclose positioning and restraining devices of this general design. The patents to Miller and Martin both disclose arm restraint systems which include, for each arm of an ejection seat occupant, a sleeve to which an elongated flexible tape or line is connected at two spaced points, one adjacent the wrist and the other between the shoulder and elbow. A guide ring may slide along the arm line, and another tension line is connected to the guide ring and also to the aircraft floor through a one-way snubber block. Upon ejection occurring, the tension line pulls on the guide ring causing the latter to begin sliding down the arm line from the elbow toward the wrist. In doing so, the guide ring pulls the arm line into a V-shape which simultaneously pulls the arm into a restrained position wherein the elbow is intended to be held against the side of the seat occupant's body and the wrist against the occupant's thigh.
However, neither the restraint system of Miller nor Martin provide any positive connection between the occupant's arm and body to ensure that arm flailing at the elbow cannot occur under some windblast conditions. Consequently, a need exists for improvement of arm restraint systems to provide greater assurance that arm flail and resulting injuries will most likely not occur.